There is known correction processing for changing a color specified in a scan image represented by scan data to another color. As an example of the correction processing, deleting an object of a specified color from a scan image is performed by changing the specified color in the scan image to a background color. For example, if a scan image includes ruled lines and characters, this correction processing can be used to delete the ruled lines from the scan image before executing character recognition processing, thereby improving recognition accuracy of the characters in the scan image.